Fix display of R2L lines in partial-width windows.

 src/xdisp.c (init_iterator): Don't use it->bidi_p before it is
 assigned the correct value.
 (extend_face_to_end_of_line): Account for truncation and
 continuation glyphs in R2L rows when one of the fringes is not
 displayed.
 (display_line): Don't assign negative X offset to a row if we are
 going to produce a truncation glyph for it.  When handling
 truncated R2L rows, consider the width of the left fringe instead
 of the right one.
 (produce_special_glyphs): Fix bogus assignments.

2 files changed, 57 insertions, 13 deletions

diff --git a/src/ChangeLog b/src/ChangeLog
index c32b4c44988..09b606d1dd5 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,17 @@
+2014-09-15  Eli Zaretskii  <eliz@gnu.org>
+
+        Fix display of R2L lines in partial-width windows.
+        * xdisp.c (init_iterator): Don't use it->bidi_p before it is
+        assigned the correct value.
+        (extend_face_to_end_of_line): Account for truncation and
+        continuation glyphs in R2L rows when one of the fringes is not
+        displayed.
+        (display_line): Don't assign negative X offset to a row if we are
+        going to produce a truncation glyph for it.  When handling
+        truncated R2L rows, consider the width of the left fringe instead
+        of the right one.
+        (produce_special_glyphs): Fix bogus assignments.
+
 2014-09-14  Eli Zaretskii  <eliz@gnu.org>
 
         * w32.c (fcntl): Support O_NONBLOCK fcntl on the write side of
diff --git a/src/xdisp.c b/src/xdisp.c
index 6b327c84290..909349b81b3 100644
--- a/src/xdisp.c
+++ b/src/xdisp.c
@@ -2994,12 +2994,8 @@ init_iterator (struct it *it, struct window *w,
 
       /* If we truncate lines, leave room for the truncation glyph(s) at
          the right margin.  Otherwise, leave room for the continuation
-         glyph(s).  Done only if the window has no fringes.  Since we
-         don't know at this point whether there will be any R2L lines in
-         the window, we reserve space for truncation/continuation glyphs
-         even if only one of the fringes is absent.  */
-      if (WINDOW_RIGHT_FRINGE_WIDTH (it->w) == 0
-          || (it->bidi_p && WINDOW_LEFT_FRINGE_WIDTH (it->w) == 0))
+         glyph(s).  Done only if the window has no right fringe.  */
+      if (WINDOW_RIGHT_FRINGE_WIDTH (it->w) == 0)
         {
           if (it->line_wrap == TRUNCATE)
             it->last_visible_x -= it->truncation_pixel_width;
@@ -3064,6 +3060,19 @@ init_iterator (struct it *it, struct window *w,
          iterator.  */
       if (it->bidi_p)
         {
+          /*  Since we don't know at this point whether there will be
+              any R2L lines in the window, we reserve space for
+              truncation/continuation glyphs even if only the left
+              fringe is absent.  */
+          if (base_face_id == DEFAULT_FACE_ID
+              && WINDOW_LEFT_FRINGE_WIDTH (it->w) == 0
+              && WINDOW_RIGHT_FRINGE_WIDTH (it->w) != 0)
+            {
+              if (it->line_wrap == TRUNCATE)
+                it->last_visible_x -= it->truncation_pixel_width;
+              else
+                it->last_visible_x -= it->continuation_pixel_width;
+            }
           /* Note the paragraph direction that this buffer wants to
              use.  */
           if (EQ (BVAR (current_buffer, bidi_paragraph_direction),
@@ -19334,7 +19343,18 @@ extend_face_to_end_of_line (struct it *it)
 
           for (row_width = 0, g = row_start; g < row_end; g++)
             row_width += g->pixel_width;
-          stretch_width = window_box_width (it->w, TEXT_AREA) - row_width;
+
+          /* FIXME: There are various minor display glitches in R2L
+             rows when only one of the fringes is missing.  The
+             strange condition below produces the least bad effect.  */
+          if ((WINDOW_LEFT_FRINGE_WIDTH (it->w) == 0)
+              == (WINDOW_RIGHT_FRINGE_WIDTH (it->w) == 0)
+              || WINDOW_RIGHT_FRINGE_WIDTH (it->w) != 0)
+            stretch_width = window_box_width (it->w, TEXT_AREA);
+          else
+            stretch_width = it->last_visible_x - it->first_visible_x;
+          stretch_width -= row_width;
+
           if (stretch_width > 0)
             {
               stretch_ascent =
@@ -20475,9 +20495,17 @@ display_line (struct it *it)
                   /* When the last glyph of an R2L row only fits
                      partially on the line, we need to set row->x to a
                      negative offset, so that the leftmost glyph is
-                     the one that is partially visible.  */
-                  if (row->reversed_p && new_x > it->last_visible_x)
-                    row->x = it->last_visible_x - new_x;
+                     the one that is partially visible.  But if we are
+                     going to produce the truncation glyph, this will
+                     be taken care of in produce_special_glyphs.  */
+                  if (row->reversed_p
+                      && new_x > it->last_visible_x
+                      && !(it->line_wrap == TRUNCATE
+                           && WINDOW_LEFT_FRINGE_WIDTH (it->w) == 0))
+                    {
+                      eassert (FRAME_WINDOW_P (it->f));
+                      row->x = it->last_visible_x - new_x;
+                    }
                 }
               else
                 {
@@ -20551,7 +20579,10 @@ display_line (struct it *it)
                   that they are cropped at the right edge of the
                   window, so an image glyph will always end exactly at
                   last_visible_x, even if there's no right fringe.  */
-               && (WINDOW_RIGHT_FRINGE_WIDTH (it->w) || it->what == IT_IMAGE))
+               && ((row->reversed_p
+                    ? WINDOW_LEFT_FRINGE_WIDTH (it->w)
+                    : WINDOW_RIGHT_FRINGE_WIDTH (it->w))
+                   || it->what == IT_IMAGE))
               ? (it->current_x >= it->last_visible_x)
               : (it->current_x > it->last_visible_x)))
         {
@@ -25719,14 +25750,13 @@ produce_special_glyphs (struct it *it, enum display_element_type what)
 
   temp_it.dp = NULL;
   temp_it.what = IT_CHARACTER;
-  temp_it.len = 1;
   temp_it.c = temp_it.char_to_display = GLYPH_CHAR (glyph);
   temp_it.face_id = GLYPH_FACE (glyph);
   temp_it.len = CHAR_BYTES (temp_it.c);
 
   PRODUCE_GLYPHS (&temp_it);
   it->pixel_width = temp_it.pixel_width;
-  it->nglyphs = temp_it.pixel_width;
+  it->nglyphs = temp_it.nglyphs;
 }
 
 #ifdef HAVE_WINDOW_SYSTEM